JP3109105B2 - Digital angiography device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medical X-ray examination system, and more particularly to a digital angiography apparatus used for cardiovascular examination and the like.

[0002]

2. Description of the Related Art In a digital angiography apparatus, two types of digital image processing are usually performed in order to improve the quality of a perspective image or a captured image. That is, one of them is recursive filtering, which removes noise components of an image by giving a time-integral effect to the image. The degree of the effect varies depending on the recursive filter coefficient. When the coefficient is increased, the S / N ratio increases, but on the contrary, blur occurs due to the motion of the image. The second is real-time edge enhancement processing, in which a spatial filter is applied to give a differentiating effect to the image to increase the sharpness of the image. If this effect is too strong, the image will have noticeable noise.

Therefore, in a conventional digital angiography apparatus, an adjustment button for adjusting a recursive filter coefficient and a degree of enhancement of real-time edge enhancement is provided, and these adjustments are performed when an operator manually presses these buttons. I have to.

[0004]

However, the digital angiography apparatus targets many imaging parts, and accordingly, there are many acquisition modes. Therefore, not only does the required S / N ratio and sharpness of the image differ depending on the image to be obtained, but also the amount of movement differs depending on the region, so that each time the operator frequently presses the adjustment button to perform the optimal setting. It is necessary and very complicated.

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a digital angiography apparatus improved so as to reduce the trouble of adjusting the recursive filter coefficient and the degree of enhancement of edge enhancement.

[0006]

In order to achieve the above object, in a digital angiography apparatus according to the present invention, an operator sets an acquisition mode and an acquisition speed of digital data of an X-ray image, and the mode and the speed are set. When the recursive filter coefficient and the edge enhancement degree are set, the recursive filter coefficient and the edge enhancement degree are stored in correspondence with the set combination of the collection mode and the collection speed. When the acquisition speed is set, the recursive filter coefficient and the edge enhancement degree are read out for the same combination. When the acquisition mode and the acquisition speed are determined, the parameters set in the past in the combination of the acquisition mode and the acquisition speed are read and referenced. Therefore, the read parameters can be used as they are or can be used after being modified.
Since the correction is a correction of a parameter set in the past for the same combination of the collection mode and the collection speed, the correction is often small, and the optimum parameter can be easily obtained, thereby reducing the burden on the operator. be able to.

[0007]

An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an entire system of a digital angiography apparatus according to an embodiment of the present invention. In this figure, X-ray tube 1 has X
The X-ray tube 1 is supplied with a high voltage from the X-ray tube high voltage device 17.
The X-ray beam 2 emitted from is transmitted through the subject 18 and enters the image intensifier 3, and the X-ray transmission image is converted into a visible light image. This visible light image is displayed on TV camera 4
Is converted to a video signal by the A / D conversion circuit 5
Is converted into digital data. The digital data of the video signal is subjected to image processing by the image processing circuit 9, returned to an analog video signal by the D / A conversion circuit 10, and displayed by the TV monitor device 11. The digital data after the image processing is simultaneously recorded on the high-speed magnetic disk device 16.

The image processing circuit 9 includes a recursive filter processing circuit 6, a subtraction circuit 7, and a real-time edge enhancement processing circuit 8.

The recursive filter processing circuit 6 has a configuration as shown in FIG. 2. Each pixel value of the input image data is multiplied by 1 / K by a weighting circuit 61 and sent to an adding circuit 63. The addition circuit 63 includes a frame memory 6
4 is obtained by multiplying each pixel value of the image data of the previous frame stored in 4 by {1- (1 / K)} by the weighting circuit 62, and the same pixels are added, and the added output Are stored in the frame memory 64 again. Therefore, as shown in FIG.
When a large number of image data 31 of each frame having 2 are sequentially obtained with the passage of time, the value of the past frame is added to the value of each pixel 32 of the current frame at a smaller ratio than in the past. As a result, an afterimage effect is provided, and noise is greatly reduced when the subject 18 is not moving. On the other hand, when the subject 18 is moving, the image is blurred due to the afterimage effect. Therefore,
It is necessary to change the recursive filter coefficient K depending on the image.

The subtraction circuit 7 performs a subtraction operation between the image data before and after the injection of the contrast agent to extract an image of a part such as a blood vessel where the contrast agent exists.

[0011] Real-time edge enhancement processing circuit 8
Converts the value P (x, y) of each pixel of the image data 31 as shown in FIG. 4 into, for example, the eight surrounding pixels, its own value, and the corresponding value of a weight matrix composed of 3 × 3 elements. The product with the element is obtained, and the product is obtained as the sum of the nine products. By such processing, spatial filtering of the image is performed, and the sharpness of the image is increased by the spatial differential effect of the image. In this real-time edge enhancement processing circuit 8, the effect increases or decreases depending on the value of each element of the above-mentioned weight matrix. However, if the intensity is too strong, an image in which noise is conspicuous is obtained.
It is necessary to optimize it according to the ratio and the like.

The acquisition mode / acquisition speed setting circuit 14
Is provided, so that the operator can arbitrarily set a collection mode and a collection speed. Normal,
A digital cine mode, a pulse mode, a serial mode, a continuous mode, or the like with a high-definition image is set as an image data acquisition mode at the time of photographing according to an examination site or an examination purpose. .
This will be set in the range of 5 fps to 60 fps.
In these modes, the recursive filter coefficient needs to be reduced because the former corresponds to a part where the movement of the subject such as the heart is more rapid. When the collection speed is set to be high, it is necessary to reduce the recursive filter coefficient because it is a site where the subject 18 moves rapidly.

Further, a parameter manual setting circuit 15
Is provided so that the operator can arbitrarily set the recursive filter coefficient and the degree of enhancement of edge enhancement.

The setting circuits 14 and 15 are connected to the parameter storage circuit 12 so that each set parameter is set for each combination of the collection mode and the collection speed so as to distinguish between photographing and fluoroscopy each time the setting is performed. It is memorized.

When the parameters are stored in the storage circuit 12 and the operator sets the collecting mode and the collecting speed, the latest several parameters for the combination are read out, and the average value of the parameters is averaged. It is calculated by the calculation circuit 13. The parameters thus obtained are displayed on, for example, a part of the screen of the TV monitor device 11, and are sent to the recursive filter processing circuit 6 and the real-time edge enhancement processing circuit 8 after confirmation by the operator. Therefore, the storage parameters for the last several times are averaged and set, and there is a learning effect of approaching the optimum value.

In this embodiment, the average value calculating circuit 13
Is used to calculate the average value of the storage parameters for the last several times, but more simply, for the same combination of acquisition mode and acquisition speed, the recursive filter coefficient previously set manually by the operator, the degree of enhancement of edge enhancement, etc. Is also conceivable.

[0017]

As described above, according to the embodiment,
According to the digital angiography apparatus of the present invention, when the acquisition mode and the acquisition speed are set according to the imaging region and the purpose of inspection during fluoroscopy or imaging, those set in the past for the recursive filter coefficient and the edge enhancement emphasis degree are used. Since it is read out, it can be used as it is, or it can be used by slightly modifying it manually, setting the optimal parameters is easy, and complicated adjustment work by the operator is reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a digital angiography apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram of a recursive filter processing circuit of the embodiment.

FIG. 3 is a diagram for explaining the operation of the recursive filter processing circuit of the embodiment.

FIG. 4 is an exemplary view for explaining the operation of the real-time edge enhancement processing circuit of the embodiment.

[Explanation of symbols]

Reference Signs List 1 X-ray tube 2 X-ray beam 3 Image intensifier 4 TV camera 5 A / D conversion circuit 6 Recursive filter processing circuit 7 Subtraction circuit 8 Real-time edge enhancement processing circuit 9 Image processing circuit 10 D / A conversion circuit 11 TV monitor device Reference Signs List 12 parameter storage circuit 13 average value calculation circuit 14 acquisition mode / acquisition speed setting circuit 15 parameter manual setting circuit 16 high-speed magnetic disk drive 17 X-ray high voltage device 18 subject 31 image data 32 pixel 33 weighting matrix 61, 62 weighting circuit 63 Adder circuit 64 frame memory

Claims (1)

(57) [Claims] A means for obtaining digital data of the X-ray image; a means for performing recursive filtering on the image data; a means for performing edge enhancement processing on the image data; Means for setting a data collection mode and a collection speed, means for setting a recursive filter coefficient and an edge enhancement degree, and a set collection mode and a collection rate for the set recursive filter coefficient and the edge enhancement degree. Storage means for storing the combination corresponding to the combination and reading out the recursive filter coefficient and the edge enhancement degree corresponding to the combination when the same acquisition mode and acquisition speed are set later. Digital angiography device.